A very large number of homes and offices now have computers and connections to the Internet. Computers have increased personal and professional productivity, enhanced entertainment options, and provided numerous functions that were not feasible in the past. Data communication over the Internet between computer users has also expanded greatly during the last decade. The Internet and other networks that employ the Internet protocol (IP) can also support voice communications by transferring packets of audio data. Voice communication over the Internet is commonly referred to as voice over IP (VOIP). However, IP networks are not optimized for continuous, real-time voice communication. Instead, IP networks are currently optimized to ensure data integrity and minimize data losses. To minimize data losses, IP networks must sometimes resend data packets that were not properly received, which slows the communication. Although these techniques ensure data integrity, the resulting latencies can cause relatively poor quality voice communication that sounds choppy and delayed. In addition, enterprises and home networks often “firewall” products to secure their networks and Network Address Translators (NATs) to increase the number of endpoints that can share an IP address. These products make it difficult to directly address end users across the Internet and they have slowed the adoption of VOIP.
Consequently, most voice communication is still carried out over the conventional public switched telephone network (PSTN). The PSTN was designed to provide reliable, real-time voice communication, at an acceptable cost. To communicate over the PSTN, most consumers use a conventional analog telephone, sometimes referred to as a plain old telephone system (POTS) telephone. Many businesses use analog or digital telephones for communication through a private branch exchange (PBX) to the PSTN. A POTS telephone or a PBX telephone can also be combined with appropriate circuit components that add functionality to provide consumers with data enhanced services related to voice communications, such as caller identification (caller ID) and call waiting.
It would be desirable to integrate the best features of data communication over an IP network and voice communication through the PSTN. Some attempts have been made to bridge the PSTN and IP networks. Current bridge solutions allow data to move between the networks at specific points. Those points are typically central locations that are controlled by large telephone carriers or Internet service providers (ISPs). A few current bridging solutions provide bridge points at a user's desktop, but the bridging is very limited, as discussed in further detail below. In either case, current bridging solutions are more accurately referred to as switching solutions, not true integration solutions that share communication among standard telephones, the PSTN, digital computing devices, and/or IP networks.
FIGS. 1A-1C illustrate some of the prior art piecemeal approaches that have attempted to bridge communication between computer networks and telephone networks. FIG. 1A may be interpreted in two possible ways; the Figure may represent a configuration in which a conventional telephone 10, such as a POTS telephone, and a computing device, (e.g., a PC 20) share a single subscriber line 12 that is connected to a PSTN 30. A POTS telephone 10 and PC 20 typically share subscriber line 12 through a conventional modem 14, such as a 56 kilobyte modem. When interpreted in this manner, subscriber line 12 is limited to a single function at a time—either voice communication or data communication. Conventional voice communication would include PSTN audio signals, and signaling data for call control, such as on/off hook detection, dual tone multi-frequency (DTMF) encoding/decoding, and ring detection. Conventional voice communication may also include other signaling data, such as frequency shift keying (FSK) data for caller ID, that can be used by POTS telephone 10 or an auxiliary FSK device 16. However, the signaling data in this prior art configuration cannot be used by PC 20, because PC 20 does not directly recognize communications that conform to PSTN protocols and data communications cannot be multiplexed through conventional modem 14. PC 20 may only access subscriber line 12 via conventional modem 14 when POTS telephone 10 is not in use. Computer data communication from PC 20 is routed through PSTN 30 to a media gateway 32. Media gateway 32 is typically a point of presence (POP) device at an ISP that transfers data signals to an IP wide area network (WAN) 40, such as the Internet. While connected to IP WAN 40, a user can make VOIP calls through PC 20 with a headset 18, or using a conventional microphone and speakers (neither shown) that are attached to PC 20. However, the user cannot switch to a PSTN voice call without losing the Internet connection, which is especially inconvenient to users who have paid for a conventional PSTN call waiting function.
Two approaches have been taken to solve the call waiting problem. One is an Internet call waiting service, which displays a notice of an incoming call on a user's PC while the user's PC is connected to the Internet. When the user's PC is connected to the Internet, special software on the user's PC informs a call management service that the user is online. The user must also have a conventional PSTN call forwarding service. When the user is online, any incoming PSTN calls are automatically routed to the provider of the call management service. The call management service provider detects the forwarded PSTN call, and sends an IP message to the user's computer, informing the user of the incoming PSTN call. The user may then choose to ignore the incoming PSTN call or accept the incoming PSTN call, thereby terminating the Internet connection. An example of Internet call waiting service is INTERNET CALL MANAGER™, which is provided by InfoInteractive Corp. However, Internet call waiting is only useful while the user is online, and does not replace conventional PSTN call waiting when the user is not online.
An alternative approach includes a call waiting modem, such as that distributed by ActionTec Electronics, Inc. While the user is online, a call waiting modem can detect an incoming signal from a user's conventional PSTN call waiting service. Typically, the modem will notify the user of a waiting call with a light or sound emanating from the call waiting modem. The user may then answer the waiting call with a conventional POTS telephone and talk for a limited amount of time (e.g., seven seconds) without losing the Internet connection. If the user ends the call within the limited amount of time, the user may continue using the Internet connection. If the user does not end the call within the limited amount of time, the call waiting modem automatically terminates the Internet connection.
FIG. 1A may alternatively represent a configuration comprising a digital subscriber line (DSL) modem. The media gateway may comprise a central office (CO) that lets voice signals continue on the PSTN, and switches data signals onto the IP WAN. The CO typically includes a switch or splitter that separates PSTN voice signals from IP data signals, and a DSL Access Multiplexer (DSLAM) that multiplexes data signals from multiple client devices onto a single connection to the IP WAN. With DSL service, a user can make voice calls over the PSTN with a conventional POTS telephone while maintaining a continuous connection with the Internet at the same time. With these two separate lines of communication, the user can hold a VOIP conversation over the Internet through the user's PC, and also hold a conventional voice call over the PSTN through the user's POTS telephone. However, the user has no control over bridging between the PSTN and the IP WAN that occurs in the CO. Thus, the PSTN and IP WAN are still effectively separate at the user's desktop. The user cannot conference a PSTN voice call with a VOIP call. Also, the user cannot benefit from PSTN added functions, such as caller ID and call waiting, through the user's PC.
Under this latter interpretation of FIG. 1A, other desktop bridging attempts have been made, but are typically limited to selectively switching between IP and PSTN networks. For example, a device called INTERNETPHONEWIZARD™, which is also distributed by ActionTec Electronics, Inc., enables a user to switch between a PSTN voice call and a VOIP call with a single conventional POTS telephone. The user connects the POTS telephone to the INTERNETPHONEWIZARD, as well as a PSTN line. The user then connects the INTERNETPHONEWIZARD to a PC via a universal serial bus (USB) port or by coupling with a peripheral component interconnect (PCI) bus in the PC. The user can make a VOIP call from the POTS telephone through the PC using a broadband connection with the Internet, such as through the DSL modem. If desired, the user can switch to a PSTN voice call without losing the internet connection. However, the PSTN call and the VOIP call cannot be conferenced together for a three-way call with the POTS phone. Also, added PSTN functions, such as caller ID, cannot be accessed by the PC.
FIG. 1B represents another typical configuration whereby the PSTN and IP WAN remain separate. This is often the case in offices. The conventional POTS or PBX phones are connected to the PSTN in a conventional manner. The PC is connected to a local area network (LAN) 35, for communication with other local PCs and/or peripheral devices. LAN 35 is connected to IP WAN 40 through a POP device and/or a Network Access Point (NAP) 36, which are often controlled by an ISP. Thus, VOIP calls and other IP communications are kept entirely separate from the PSTN.
FIG. 1B may also represent a configuration comprising broadband modem access to the Internet through an ISP. If a broadband modem 34, such as a cable modem or a DSL modem, is under the user's control, the INTERNETPHONEWIZARD may be used to switch the POTS telephone between the PSTN and the Internet thought the PC, as described above. However, the same limitations apply to this configuration. Namely, a PSTN call and the VOIP call cannot be conferenced together for a three-way call with the POTS phone, and added PSTN functions cannot be accessed by the user's PC.
FIG. 1C represents a configuration wherein the PSTN is eliminated, and the POTS telephone is replaced with an IP telephone 21 that uses IP communication instead of analog PSTN communication. All calls are VOIP calls and are typically routed through an Internet telephony service provider (ITSP) that specializes in VOIP services. This configuration may also include wireless communication to a personal data assistant (PDA) telephone 23, so that the PDA telephone can be used for VOIP calls. However, as indicated above, VOIP calls are often not as clear and reliable as conventional PSTN calls. Because IP communication was not designed for continuous, real-time voice communication, it allows for processing latencies, transmission latencies, dropped data packets, retransmitted data packets, and has other characteristics that help to ensure data integrity. However, as indicated above, these characteristics of IP communication often make VOIP calls sound choppy and delayed.
Some attempts have been made to reduce delays, dropped packets, and other problems for VOIP calls. For example, Global IP Sound, Inc. has developed software that can run on PCs, PDAs, and other local computing devices and interpolates voice data in place of dropped data packets, reduces local processing delays, reduces echo, and provides other improvements. Nevertheless, the PSTN still generally provides higher quality voice communication in a more cost effective manner for most users, especially home users, than VOIP communication. Thus, it is desirable to retain use of the PSTN for clear, inexpensive voice calls, but it is also desirable to utilize PC processing power and IP communication.
There is thus a clear motivation to integrate computing devices, telephones, and telephone networks locally, e.g., at a client desktop. In general, local integration should include signaling data (sometimes referred to as “call control data”) and audio data (sometimes referred to as “voice transport”), along with digital computing data. For example, audio integration should enable a user to conference a PSTN call and a VOIP call together. Integration of signaling data at the client desktop should enable a user to employ both PSTN call control data and IP WAN data in the user's PC to log both PSTN and VOIP calls on the user's PC, control incoming PSTN calls with the PC, use a POTS telephone to control other networked devices, and implement a host of other applications and functions.